Printed products, particularly multilayer, folded printed products are typically spread out by rotary machines or from rolls in scale formation for further processing purposes. For three reasons it is advantageous to have buffer stores or buffers between the laying out of such scale flows and their further processing. It firstly makes it possible to avoid or at least reduce any upstream transmission of problems and systematic irregularities. Secondly, gaps in the flows can be closed and, thirdly, the scale flow can be simultaneously timed. In the case of a fault or problem in further processing, which consequently takes place more slowly or even stops, the buffer store receives the products occurring during an unavoidable reaction time for a supply reaction or even makes it possible to bridge a relatively short processing break by merely slowing down the supply and correspondingly filling of the buffer, which renders unnecessary the stopping and reaccelerating of large masses. If the further processing involves systematic irregularities in such a way that the supplied product is not continuously used for the further processing stage, such as e.g. during personalized insertion, the supply can still continuously supply products to the buffer but with a correspondingly lower capacity. In the case of problem-free, continuous further processing it is still advantageous to operate with a buffer, so that gaps in the supplied scale flow can be eliminated without having any effects on the course of the further processing. Thus, the buffer serves as a collecting or absorbing station for faults and irregularities both upstream and downstream.
Such buffer storage methods and apparatuses are e.g. described in the Applicant's U.S. Pats. Nos. 4,887,809, 4,892,186 and 4,201,286. The buffer systems described therein operate with buffer means (clips, hooks, grippers, brake cams), which over a buffer section of constant length act on the printed products of the scale flow, i.e. convey them more or less actively and the number of buffer means on the buffer section and therefore the distance between the buffer means is variable. The average distance between the buffer means on the buffer section is smaller with a full buffer than with an empty one, because when the buffer is full more buffer means are positioned on the buffer section. Thus, the described buffer systems are based on the idea of a constant length buffer section with a variable spacing between the buffer means. The variable spacing between the buffer means is e.g. brought about by the free mobility of the buffer means along a movement path, in which they are shoved by the following buffer means, or by elastic connections between the buffer means, which are pulled by the leading buffer means.
All the described buffer or buffer storage systems suffer from the disadvantage that they have individually guided elements, which cannot be driven by standard pulling means, such as chains and which must be timed in again after buffer storage and that in most cases the printed products have to be transferred to the buffer means in order to be conveyed over the buffer section, which usually makes it necessary to have special spatial or three-dimensional arrangements. In addition, the described systems require numerous sensors oriented on the printed products not only for measuring the filling state of the buffer for the control of the spreading out and/or further processing, but also for detecting and closing gaps in the supplied scale flow. Such sensors have to be reset e.g. on changing the product format.